Advanced communications satellites are to utilize millimeter wave RF frequencies for communications purposes. The antennas in those satellite communications systems are intended to be directional and thus alternatively provide spot and broad area coverage over selected geographic areas on earth. For this purpose the use of dichroic surfaces as reflectors and subreflectors is a primary means for obtaining in the antennas adequate RF channel separation and physical compactness desired in satellite applications. An existing process for producing dichroic RF reflecting surfaces is to apply a metalized dichroic pattern, a series of spaced dipoles, on a curved surface, such as a parabolic shaped surface, using an "segmented orange skin" approach; one in which the metal pattern is fabricated and then oriented over and stuck onto the parabolic surface in small pieces. This approach is time consuming and costly. Further, although useful at lower frequencies, at the higher millimeter wave frequencies, the process results in butt-joint discontinuities; mechanical protrusions in the surface that occur at the juncture of two separately cut metal pieces that are attached to the surface side by side. These discontinuities are unacceptable at millimeter wave frequencies, at which a quarter wavelength measures approximately 0.075 inches, because they effectively change the antennas radiation distribution pattern. In addition to antenna application, other applications exist in which precise metalization of non-planar or irregular three dimensional surfaces is required, such as with printed circuits that are to conform to irregular shapes and three dimensional RF strip lines, a form of microwave transmission line.
An object of the invention is to provide a fast and effective process for fabricating complex intricate metal patterns on a non-planar curved surface. A secondary object is to provide a process for producing millimeter wave dichroic parabolic antenna reflector.